Field of the Invention
The present invention relates to a driving apparatus and an article processing apparatus.
Description of the Related Art
For example, a galvano motor or a linear motor is used in an article processing apparatus such as a laser processing apparatus, a semiconductor manufacturing apparatus, or the like. Among them, the galvano scanner performs positioning of, with high precision, a mirror attached to a shaft of a rotary motor (galvano motor), and then a laser beam which is reflected by the mirror. As a detector that detects a rotation angle for highly accurate positioning, an electrostatic capacitance sensor, an optical encoder, or a magnetic encoder is used. On the other hand, the linear motor performs positioning for an object to be processed such as a wafer, a mask, or the like with high accuracy. Furthermore, there are an absolute type and an incremental type for encoders. Among them, the incremental-type encoder (hereinafter referred to as “incremental encoder”) may detect the displacement amount of an object to be processed from an increase/decrease in pulse with respect to the displacement of a scale. However, in the incremental encoder, a sensor for detecting a reference position (zero point) is separately required for specifying an absolute position. Accordingly, Japanese Patent Laid-Open No. H9-229713 discloses an incremental encoder that outputs the phase Z signal indicating a reference position in addition to the phase A and phase B signals indicating a relative position. In the electrostatic capacitance sensor, the reproducibility of a detection position is affected by an environmental condition such as temperature or humidity. In order to correct a measurement value affected thereby, a sensor for detecting a reference position may be separately required.
In the driving apparatus including the incremental encoder disclosed in Japanese Patent Laid-Open No. H9-229713, a sensor for detecting a reference position needs to be separately provided as described above, and thus, there is room for further improvement in size and cost thereof.